Ringworm is a contagious infection of the skin caused by a fungus called tinea, not a worm as one might infer from its name. Ringworm presents as itchy, scaly, ring-shaped red patches on the skin, bald spots in the hair or beard, or discolored, thickened nails. The most commonly infected areas of skin are on the scalp (tinea capitis), beard (tinea barbae), body (tinea corporis), groin (tinea cruris, jock itch or diaper rash) or foot (tinea pedis or athlete's foot). Ringworm tends to occur in warm, moist areas of the body, and can be passed by touching the skin of an infected person or by making contact with an contaminated item, such as a towel, hairbrush, or pool or shower surface. Pets, especially cats, can also transmit the fungus. Skin that is wet from sweat or the environment, or that is compromised by a minor injury, is more susceptible to an invasion of ringworm fungus.
The skin patches of ringworm have sharply defined borders and may present as rings, darker red at the perimeter and skin-toned within. Crusty or oozing blisters may also be present. When ringworm affects the scalp, there may be bald patches. When it affects the nails, the nails may discolor, thicken or even begin to decompose. Ringworm is generally diagnosed by a simple physical examination. Other methods of detection include lighting the skin with a blue light which causes the fungus to glow, administering a KOH exam during which a skin scraping is microscopically examined, or taking a skin culture or biopsy.
Once ringworm has been diagnosed, it is usually treated with over-the-counter antifungal powders or creams. It is also necessary to make sure the skin is kept clean and dry and that clothing and sheets are washed often to prevent reinfection. In especially resistant cases of ringworm, where the condition doesn't respond or worsens after treatment, or where a bacterial infection develops, more aggressive treatment is required. At this time, stronger antifungal medications, either topical or oral, will be prescribed. In order to prevent a recurrence of ringworm, the skin should continually be kept clean and dry, irritating clothing should be avoided, and antifungal powders or creams should be used prophylactically.